Montana Field Guide

Swainson's Hawk - Buteo swainsoni

Adults are dark brown above, and white with chestnut-brown bib below; tail grayish-brown, finely barred, becoming lighter toward the base. In flight, the wing undersides appear two-toned, with the flight feathers dark and the leading edge of the wing white. The wings of Swainson's hawks are slightly more pointed than those of other buteos. Dark-phase Swainson's hawks appear all dark brown above and below and on the entire wing undersides, making them look like a miniature eagle. Intermediate color phases occur, with dark brown bibs and chestnut barring on the belly. Immatures lack the bib and are more strongly barred or streaked underneath. Swainson's hawks are slightly smaller then red-tailed hawks, and have longer narrower wings than other buteos. Swainson's hawks range in length from 18-22 inches, and have a wingspan of 48-52 inches.

All other buteo hawks have white flight feathers. red-tailed hawks have a dark belly band and no bib, while swainson's hawks have a bib, but no belly band.

Montana Range

Swainson's hawks leave in late September, migrating to Argentina for the winter. They often migrate in large flocks (FWP). Bozeman migr.: 4/25-5/15 & 9/2-9/10; no detectable peaks (W of main migr. path) Migration late Apr, early Sep. (Davis 1961).

Swainson's hawks nest in river bottom forests, brushy coulees, and shelterbelts. They hunt in grasslands and agricultural land, especially along river bottoms (FWP). In Bozeman area, the birds inhabit the drier, open parts of the Gallatin valley (Skaar 1969).

Swainson's hawks prey on a wide variety of small mammals, songbirds and insects.

Formerly rare in the Fortine area, but not seen in summer for 30 years. Has apparently decreased in numbers in the Bozeman area in the last century (Skaar 1969).

Flimsy nests are built in trees and shrubs, often as low as four feet from the ground. Swainson's hawks are more tolerant of humans than other hawks, and will often nest close to occupied houses. One to three eggs are laid in May, and incubated for about 28 days. The young fledge in late July and August (FWP). Nests with eggs range from early May - mid July, but June is the common nesting month (Davis 1961).